IgG and IgM rubella antibodies were measured in dried blood samples from the neonatal metabolic screening program. Of 6613 samples from four central screening laboratories, 289 did not contain rubella IgG antibodies, indicating that only 4.3% of the mothers at term were not immune to the rubella virus in the spring of 1984. The proportion of women at term who were not immune was 9.3% in 1979. Rubella IgM was detected in nine of 37,000 samples; congenital rubella infection was confirmed serologically in eight infants. Of the infected babies, three showed severe clinical findings. We suggest that rubella IgG and IgM should be determined regularly in the surplus material of metabolic screening centers, thus giving the opportunity to detect infected infants. The screening procedure is also useful as a serologic tool for monitoring immunity patterns in women, and thus the effectiveness of vaccination programs.